This invention relates, in general, to semiconductor devices, and more particularly to a semiconductor package having leads that break-away from supports.
It is common in the semiconductor art to employ surface mount packages for placement on printed circuit boards and the like. Typically, the leads of a surface mount package are soldered directly to the printed circuit board so that electrical coupling occurs therebetween. An often arising problem is that the surface mount package and the printed circuit board on which it is mounted have different coefficients of thermal expansion. As a result, thermal contraction causes stress throughout the package and printed circuit board, especially at the leads and solder joints. The stress often causes the solder joints to break and the semiconductor package to function improperly.
One solution to reduce the problems caused by thermal contraction stress is to employ surface mount packages having thin metal leads that are flexible. The thin leads flex during thermal contraction and reduce damage to both the leads and solder joints. However, flexible leads on surface mount packages have a tendency to become misaligned. Lead misalignment results in open solder joints and has many deleterious effects in the mounting of surface mount packages. These problems are especially prevalent when very thin leads are required due to high lead counts and the like.
Accordingly, it would be highly desirable to have a semiconductor package that may be employed in surface mount applications that adequately counters the stress problems caused by the differing thermal expansion coefficients of the package and the printed circuit board on which the package is mounted while not having serious misalignment problems.